(a) Field of the Invention
The present invention relates to a method for controlling a damper clutch of an automatic transmission, and more particularly, to a method for performing duty control in releasing the damper clutch when a down-shift is executed when an accelerator pedal is depressed in a sports mode and thereby reducing a gear-shift
(b) Description of the Related Art
Generally, an automatic transmission automatically shifts gears according to a driving state. However, a driver can directly input a gear-shift signal into the automatic transmission if necessary.
The gear-shift signal inputted by a driver is divided into an xe2x80x98up-shiftxe2x80x99 signal by which the gear shifts upward and a xe2x80x98down-shiftxe2x80x99 signal by which the gear shifts downward.
The gear-shift signal is inputted by moving a shift lever from a general shift mode column comprising P-R-N-D to a sports mode column. The sports mode is provided with means for generating xe2x80x98+xe2x80x99 or xe2x80x98xe2x88x92xe2x80x99 signals for shifting gears. Therefore, the gear-shift signal can be generated by a manipulation of the shift lever, and the generated gear-shift signal is inputted into a transmission control means.
In the automatic transmission, engine torque is transmitted to the transmission via a torque converter. The torque converter transmits engine torque through a flow of working fluid, and therefore slip occurs, but a damper clutch is provided inside the torque converter to reduce this slip. In some driving states, the engine and the transmission are directly coupled by an operation of the damper clutch, and thereby fuel mileage and a power transmission ratio are improved.
When the transmission control means receives a down-shift signal from a driver in the sports mode, the transmission control means immediately releases the damper clutch.
However, if the down-shift signal is inputted in a state when an accelerator pedal is depressed, the transmission control means determines a down-shift and immediately releases the damper clutch. Therefore, a difference between the engine speed at the point when the shift is completed and the engine speed at the point the shift is started is substantial, and thus gear-shift shock occurs.
Therefore, the present invention relates to a method to solve the above problem, and it is an object of the present invention to provide a method for controlling a damper clutch by which, in performing a down-shift during the accelerator pedal being depressed in a sports mode, a transmission control means releases the damper clutch under duty control and thereby reduces the gear-shift shock.
To achieve the object above, a damper clutch release control system comprises:
a throttle position sensor for detecting an opening angle of a throttle valve;
a sports mode detecting means for detecting whether a shift lever is in a sports mode column;
a gear-shift signal detecting means for detecting a gear-shift signal generated by manipulation of the shift lever;
a damper clutch controlling the power transmission between the engine and the transmission, the damper clutch being installed inside a torque converter transmitting the rotating power of the engine to the transmission; and
a transmission control means for controlling an operation of the damper clutch through having inputted data from the throttle position sensor, sports mode detecting means and gear-shift signal detecting means.
Using the above system, the method for controlling the damper clutch by the transmission control means comprises:
(a) determining whether the down-shift signal is inputted in a state when a gear shift mode is a sports mode and a throttle valve opening angle is within a predetermined range; and
(b) performing duty control until the transmission control means outputs a down-shift start signal to the transmission if it is determined that the down-shift signal is inputted.